<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .active{
            border: 2px solid red;
        }
    </style>
</head>
  <body>
        <div id="app">
            <img v-bind:src="imgSrc" :title="imgTitle+'!!!'">
            <!-- <br>                                                   ？   ：  如果 是   就怎么 -->
        <img :src="imgSrc" :title="imgTitle+'显示'" :class="isActive?'active':''" @click="toggleActive">
        <img :src="imgSrc" :title="imgTitle+'显示'" :class="{active:isActive}" @click="toggleActive">
        <!-- 点击变色                         active取值依赖于isactive是否取值 -->
        </div>
        <!-- 开发环境版本，包含了有帮助的命令行警告 -->
        <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
        <script>
            var app=new Vue({
                el:"#app",
                data:{
                    imgSrc:"https://img0.baidu.com/it/u=2753883117,2936626650&fm=26&fmt=auto",
                    imgTitle:"壁纸",
                    isActive:false
                },
                methods:{
                 toggleActive:function(){
                     this.isActive=!this.isActive;
                 }
             }
            })
        </script>
   </body>
</html>